Definition
A graphical tool to record a process and its input output variables.
In detail
An IPO Diagram is a visual tool used to document the inputs, process steps, and output variables of a process. It helps teams clarify process boundaries and key elements before improvement, identifying potential problem points. Unlike flowcharts, IPO diagrams focus on variables rather than step sequences, often used in the problem definition phase of Six Sigma and lean projects. The output is a clear process variable table, providing a basis for subsequent analysis.
Example in practice
When analyzing a quality issue at a production line process, the team used an IPO diagram to organize the process inputs (e.g., raw materials, equipment parameters), process (operation steps), and outputs (product characteristics). By comparing ideal and actual inputs and outputs, temperature fluctuation was identified as the main source of variation. Mistake-proofing measures were then implemented for temperature control, reducing defects. The IPO diagram helped the team systematically identify key variables.